It is well known to those skilled in the art of producing composite golf club shafts that such shafts are formed by wrapping or rolling sheets of fiber materials impregnated with resin, typically epoxy, around elongated tapered tools, called “mandrels”, which are sized and shaped to form the materials into elongated, tapered tubes comprising selected numbers of layers of the composite materials. Each mandrel has a taper profile from a larger butt-end portion to a smaller tip-end portion and the cross-sectional size and shape that is desired for the inside surface of the shaft, and the number of wraps determines the wall thickness along the taper after the shaft is rolled, cured and finished in a well known manner. Typically, the outside surface of each shaft is finished to a smooth surface, and the shaft is trimmed to a pre-selected standard length, and painted before the club head and grip are assembled to produce a finished golf club.
Also well known is the fact that the amounts and types of fiber materials used in a shaft will determine two of the most important properties of the shaft, weight and longitudinal flex or bending, referred to as overall stiffness. Basically, the weight is determined by the total amount of material in the finished shaft, and the longitudinal stiffness depends primarily upon the amount of longitudinally extending fibers in a shaft. These are called “zero” ply materials or fibers because they are at substantially a zero angle with the longitudinal axis of the shaft, as opposed to so-called “angle” ply or “bias” ply materials on which the fibers are dispersed at substantially forty-give degree angles with the axis of the height. These contribute to the overall weight of the shaft and impart primarily torsional stiffness to the shaft.
Golf club shaft designers are able to produce shafts with different weights, stiffness and flex characteristics to suit the preferences of different golfers and for different clubs. For example, lighter shafts may be preferred for higher club speed, and stiffer shafts may be preferred for greater head control with a wide range of variations for adapting clubs to the tastes of a wide variety of golfers and situations. The general objective of this invention is to provide a novel method for producing golf club shafts of like flex profiles and selectively different weights, and provide a family of such shafts.